Secondary structure

Secondary structure is the general three-dimensional form of local segments of biopolymers such as proteins and nucleic acids (DNA/RNA). It is defined by the patterns of hydrogen bonds between the amino acid residues or bases. In proteins, the secondary structure is defined by patterns of hydrogen bonds between backbone amide and carboxyl groups. In nucleic acids, the secondary structure is defined by the hydrogen bonding between the nitrogenous bases.

Protein secondary structure

Protein secondary structures are the alpha helix and the beta sheet. The alpha helix is a right-handed coiled strand, with 3.6 amino acid residues per turn. The beta sheet is a pleated sheet-like structure, with the strands running antiparallel or parallel.

Nucleic acid secondary structure

Nucleic acid secondary structures are the structures formed by base pairing between individual nucleotides. These include the double helix structure of DNA and various types of loops and stems in RNA.

Methods of determination

Methods of determination of secondary structure include X-ray crystallography and NMR spectroscopy. Computational prediction methods also exist, such as the Chou-Fasman method and the GOR method.

See also

• Tertiary structure
• Quaternary structure
• Protein structure prediction
• Nucleic acid secondary structure prediction

References

Secondary structure Resources
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